Power supply device, control method thereof, and power supply system

Abstract

To provide a power supply device that increases the specific capacity of an aluminum electrolytic capacitor, a control method thereof and a power supply system.SOLUTION: An electrochemical three-electrode system 3 including a working electrode 32, a reference electrode 33, and an auxiliary electrode 31 is prepared as a power supply system 1, two output terminals 22, 23 of a power unit 2 of a power supply device are connected to the working electrode and the auxiliary electrode, respectively and current for polarizing the working electrode is output from the power unit. The control unit 5 of the power supply device detects a signal reflecting voltage between the working electrode and the reference electrode and adjusts an output current based on the signal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power supply device, a control method thereof, and a power supply system, and particularly to a power supply device, a control method thereof, and a power supply system that increase specific capacitance.

Background Art

[0002] An aluminum electrolytic capacitor includes at least a positive electrode, a negative electrode, and an electrolytic solution. Electrode foils are materials used to manufacture the positive and negative electrodes of an aluminum electrolytic capacitor and are mainly used for storing electric charges. Electrode foils are formed from high-purity aluminum foils as the main raw material through a series of processing steps such as corrosion and formation. To explain the manufacturing process of an aluminum electrolytic capacitor in more detail, after winding an anodic aluminum foil covered with a dielectric layer (i.e., an oxide film) by corrosion, a corroded cathodic aluminum foil, and electrolytic paper, it is immersed in an electrolytic solution and encapsulated in an aluminum case for manufacturing.

[0003] The quality of the electrode foil has a decisive impact on the overall performance of the aluminum electrolytic capacitor. The corrosion process and formation process of the electrode foil directly determine the performance of the aluminum electrolytic capacitor, such as its capacitance, leakage current, loss, lifespan, reliability, and volume. For example, the larger the specific capacitance of the electrode foil, the higher the unit charge amount of the electrode foil, and the smaller the volume of the aluminum electrolytic capacitor that can be manufactured at the same voltage. Therefore, the electrode foil is the part with the highest technical content and added value in the aluminum electrolytic capacitor.

[0004] In order to increase the specific capacitance of an electrode foil, generally, there are three methods: a method of improving the corrosion process to increase the surface area ratio (the first method), a method of reducing the average dielectric thickness under the operating voltage (the second method), and a method of improving the characteristics of the dielectric layer to increase the dielectric constant (the third method). In the second method, since the thickness of the dielectric layer depends on the operating voltage and the operating voltage is usually a fixed value, it cannot be improved. In the third method, since the dielectric constant of the dielectric layer is also a fixed value, it cannot be improved. Therefore, to increase the specific capacitance of the electrode foil, the best method is to improve the corrosion process to increase the surface area ratio, which is a research topic for those skilled in the art.

[0005] Therefore, it is currently an urgent task to develop a power supply device, its control method, and a power supply system that overcome the above-mentioned drawbacks.

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a power supply device, its control method, and a power supply system. The control unit detects a signal reflecting the voltage between the working electrode and the reference electrode of the electrochemical three-electrode system, compares the signal with a predetermined voltage range, and according to the comparison result, maintains the signal within the voltage range (that is, between the critical passivation potential and the over-passivation potential), that is, adjusts the output current of the power unit so that the output current is maintained near the passivation current. Thereby, the corrosion pores generated at the initial stage of etching can continue to grow, improving the production efficiency of pore expansion. At the same time, by adjusting the dynamic characteristics of the low passivation current in real time, the formation and corrosion of the passivation film on the inner surface of the corrosion pores are promoted, the corrosion pores are effectively developed in the depth direction, the production efficiency of the working electrode is increased, the uniformity of the corrosion pores is improved, and the overall specific capacitance is improved. At the same time, the remaining thickness of the working electrode after corrosion is uniformly maintained, and the bending characteristics of the working electrode are improved.

Means for Solving the Problems

[0007] To achieve the above object, an embodiment of the present invention provides a control method applied to a power supply device, including the following steps. First, prepare an electrochemical three-electrode system including a working electrode, a reference electrode, and an auxiliary electrode. Next, connect two output terminals of the power unit of the power supply device to the working electrode and the auxiliary electrode respectively, and the power unit outputs an output current for polarizing the working electrode. Then, the control unit of the power supply device detects a signal reflecting the voltage between the working electrode and the reference electrode, and adjusts the output current based on the signal.

[0008] To achieve the above object, another embodiment of the present invention provides a power supply device used in an electrochemical three-electrode system including a working electrode, a reference electrode, and an auxiliary electrode. The power supply device includes a power unit and a control unit. The power unit is provided with two output terminals respectively connected to the working electrode and the auxiliary electrode, and outputs an output current for polarizing the working electrode. The control unit is used to detect a signal reflecting the voltage between the working electrode and the reference electrode, and adjust the output current based on the signal.

[0009] To achieve the above object, another embodiment of the present invention provides a power supply system including the above power supply device and an electrochemical three-electrode system.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Embodiments for Carrying Out the Invention

[0011] Some typical embodiments showing the features and advantages of the present invention will be described in detail in the following explanation. It should be understood that the present invention can have various changes in different aspects, all without departing from the scope of the present invention, and the description and drawings are essentially used for illustrative purposes and are not intended to limit the present invention.

[0012] Refer to FIG. 1. FIG. 1 is a structural schematic diagram of the power supply system of the present invention. As shown in FIG. 1, the power supply system 1 of the present invention includes a power unit 2, an electrochemical three-electrode system 3, a corrosive liquid 4, and a control unit 5. The power unit 2 is provided with output terminals 22 and 23. The electrochemical three-electrode system 3 includes an auxiliary electrode 31, a working electrode 32, and a reference electrode 33. The auxiliary electrode 31 can be formed of a titanium plate and is connected to the output terminal 22 of the power unit 2. The working electrode 32 can be formed of a high-purity metal foil such as aluminum foil, is connected to the output terminal 23 of the power unit, and receives the output current supplied from the power unit 2. Thus, the working electrode 32 is polarized according to the output current supplied from the power unit 2. The material of the reference electrode 33 is related to the ion system of the corrosive liquid 4. For example, when the corrosive liquid is a hydrochloric acid or sulfuric acid solution, the electrode 33 can be composed of a saturated calomel electrode (SCE). The working electrode 32 and the auxiliary electrode 31 are arranged in the corrosive liquid 4, and the output current supplied from the power unit 2 passes through the working electrode 32, the corrosive liquid 4, and the auxiliary electrode 31 in sequence. At least a part of the reference electrode 33 is arranged in the corrosive liquid 4. A voltage exists between the working electrode 32 and the reference electrode 33. In the actual process, the working electrode 32, the auxiliary electrode 31, and the reference electrode 33 are immersed in the corrosive liquid 4 in the corrosion tank. However, only the corrosive liquid 4 is shown in FIG. 1, and the illustration of the structure of the corrosion tank is omitted. The control unit 5 and the power unit 2 constitute a power supply device. The control unit 5 controls the power unit 2 based on a signal reflecting the voltage between the working electrode 32 and the reference electrode 33. For example, the control unit 5 is connected to the working electrode 32 and the reference electrode 33 of the electrochemical three-electrode system 3, detects a signal reflecting the voltage between the working electrode 32 and the reference electrode 33, and adjusts the output current output by the power unit 2 via the control terminal 21 according to this signal. The signal reflecting the voltage between the working electrode 32 and the reference electrode 33 has a correlation with the output current supplied from the power unit 2, and this correlation will be described later.

[0013] Refer to FIGS. 2A and 2B in conjunction with FIG. 1. FIG. 2A is a partially enlarged schematic view showing the structure of the corrosion pits formed on the working electrode of the power supply system shown in FIG. 1, and FIG. 2B is a partially enlarged schematic view showing the structure of the oxide film formed on the working electrode of the power supply system shown in FIG. 1. Both FIGS. 2A and 2B show a part of the structure within the dotted line frame of FIG. 1, for example, a part of the structure of the contact surface between the working electrode 32 and the corrosive liquid 4 under different conditions. As for the corrosion process of the working electrode 32, first, as shown in FIG. 1, the working electrode 32 and the auxiliary electrode 31 are disposed in the corrosive liquid 4. Next, the power unit 2 supplies an output current to the working electrode 32. At this time, electrons and ions in the corrosive liquid 4 are consumed, and metal ions on the working electrode 32 enter the corrosive liquid 4, so that corrosion pits 32a are formed on the working electrode 32 (as shown in FIG. 2A), and the surface area of the working electrode 32 increases. Thereafter, the power unit 2 continues to supply an output current to the working electrode 32, so that an oxidation reaction occurs on the surface of the working electrode 32, and an oxide film 32b is formed (as shown in FIG. 2B). Next, the corrosive liquid 4 further corrodes the oxide film 32b and enlarges the corrosion pits 32a.

[0014] The capacitance per unit area (i.e., specific capacitance) of the aluminum electrolytic capacitor is correlated with the state of the corrosion pits 32a formed on the working electrode 32. Refer to FIG. 3 in conjunction with FIGS. 1 and 2A. FIG. 3 is a simplified schematic view of the coaxial capacitance of the corrosion pits shown in FIG. 2A. The collector capacitances of the distributed capacitances C1, C2,..., Cn in the figure are as follows. From this formula, it can be seen that the capacitance per unit area of the aluminum electrolytic capacitor is correlated with the depth L of the corrosion pits 32a and the radius r1 of the corrosion pits 32a. The greater the depth L of the corrosion pits 32a, the greater the capacitance per unit area of the aluminum electrolytic capacitor, and the greater the radius r1 of the corrosion pits 32a, the greater the capacitance per unit area of the aluminum electrolytic capacitor.

[0015] When the working electrode 32 is disposed in the corrosive liquid 4, a surface potential is formed on the surface of the working electrode 32, and the surface potential of the working electrode 32 has a correlation with the properties of the metal, the composition, concentration, and temperature of the corrosive liquid 4. When the output current supplied from the power unit 2 passes through the working electrode 32, the working electrode 32 is polarized, and as a result, the electrode potential changes. That is, the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 has a correlation with the output current supplied from the power unit 2, and a polarization curve can be further formed based on the correlation between the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 and the output current supplied from the power unit 2. Also, according to two formulas of the electrochemical reaction rate theory, namely, the Butler-Volmer equation and the Arrhenius equation, it can be seen that the factors affecting the electrolytic corrosion rate include the polarization potential or polarization current, the composition of the electrolyte, the temperature of the electrolyte, the concentration, the corrosion time, the electrode surface state, and the crystal structure. Among them, the greatest influence is the polarization potential or polarization current, that is, the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 or the output current supplied from the power unit 2. Therefore, hereinafter, the correlation between the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 and the output current is further confirmed, and the corrosion rate of the working electrode 32 is grasped based on the correlation. Refer to FIG. 4 in conjunction with FIGS. 1, 2A, and 2B. FIG. 4 is a schematic diagram of the polarization curve of the working electrode of the power supply system when the power voltage is under open-loop control. As shown in FIG. 4, the X-axis of the polarization curve is the signal reflecting the voltage between the working electrode 32 and the reference electrode 33, and the Y-axis of the polarization curve is the output current supplied from the power unit 2. The signal reflecting the voltage between the working electrode 32 and the reference electrode 33 in the polarization curve includes, for example, four sections: a first section, a second section, a third section, and a fourth section shown in FIG. 4. In the first section, the power unit 2 starts supplying the output current, corrosion pits 32a begin to form on the working electrode 32, and a chemical reaction also occurs between the working electrode 32 and the corrosive liquid 4, and an oxide film 32b is gradually generated. The output current supplied from the power unit 2 rises from the first current ip to the second current ib, and as a result, the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 rises from point A to point B.The corrosion rate of the working electrode 32 increases as the output current increases. When the output current supplied from the power unit 2 rises to the second current ib, the corrosion rate of the working electrode 32 reaches its maximum value, and the output current can no longer increase. Therefore, the second current ib is defined as the critical passivation current. In the second interval, the corrosion rate of the working electrode 32 decreases. That is, the output current supplied from the power unit 2 begins to decrease from the second current ib to the first current ip, and the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 rises from point B to point C. As the output current decreases, the corrosion rate of the working electrode 32 decreases. When the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 rises to point C, the output current supplied from the power unit 2 decreases and is maintained at the first current ip. Therefore, the voltage signal at point C is defined as the critical passivation potential Ep. In the third interval, the output current supplied from the power unit 2 is maintained at the first current ip, and the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 rises from point C to point D. At this time, since the corrosion rate of the working electrode 32 and the formation rate of the oxide film 32b reach a dynamic equilibrium, the output current is in a stable state at this point. That is, since this interval is the stable passivation region, the output current in this interval (i.e., the first current ip) is defined as the passivation current. Since the power unit is under open-loop control, the output current in this interval is basically a fixed value. In the fourth interval, the output current supplied from the power unit 2 continues to rise from the first current ip, the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 rises from point D to point E, and other corrosion pits 32a continue to be formed on the working electrode 32. Since the corrosion reaction at this time becomes intense, this interval is defined as the transpassivation region.

[0016] Since the pore expansion reaction process is very sensitive to the output current, when the output current decreases, the formation of the corrosion pit 32a may stop or the formation interface of the corrosion pit 32a may become discontinuous. From the above description of the polarization curve and FIG. 4, the third region is the stable growth period of the corrosion pit. At this time, the output current is low and gentle. In the third region, the corrosion rate of the working electrode 32 and the formation rate of the oxide film 32b can reach a dynamic equilibrium. As a result, the corrosion pit 32a can grow stably. Therefore, in order to achieve a better corrosion pit expansion effect, the power supply system 1 of the present invention adjusts the output current dynamically by the control unit 5 so that the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 and the output current are in the stable growth period of the corrosion pit in the polarization curve, and monitors the signal reflecting the voltage between the working electrode 32 and the reference electrode 33. As shown in FIG. 1, the control unit 5 is electrically connected to the working electrode 32 and the reference electrode 33 of the electrochemical three-electrode system 3. There are a predetermined voltage range and a current range in the control unit 5. For example, the voltage range is the third region shown in FIG. 4 (that is, between point C and point D). The control unit 5 detects the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 of the electrochemical three-electrode system 3, and adjusts the output current based on the signal. For example, the signal is compared with a predetermined voltage range, for example, it is confirmed whether the signal is within the voltage range. The control unit 5 maintains the signal within the voltage range according to the comparison result, that is, maintains the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 of the electrochemical three-electrode system 3 within the third region shown in FIG. 4, and adjusts the output current of the power unit 2 within the current range.

[0017] As can be seen from the above, in the power supply system 1 of the present invention, the control unit 5 detects a signal reflecting the voltage between the working electrode 32 and the reference electrode 33 of the electrochemical three-electrode system 3, compares the signal with a predetermined voltage range, and according to the comparison result, maintains the signal within the voltage range (that is, between the critical passivation potential and the over-passivation potential), and adjusts the output current of the power unit 2 within a current range so that the output passive current is also maintained within a certain range. Thereby, the corrosion pits 32a generated at the initial stage of etching can continue to grow, improving the production efficiency of pore expansion. At the same time, by adjusting the passive current in real time, the formation and corrosion of the passive film on the inner surface of the corrosion pits 32a are promoted, the corrosion pits 32a are effectively developed in the depth direction, the production efficiency of the working electrode 32 is improved, the uniformity of the corrosion pits 32a is improved, and the overall specific capacitance is improved. At the same time, the remaining thickness of the working electrode 32 after corrosion is uniformly maintained, and the bending characteristics of the working electrode 32 are improved.

[0018] Refer to FIG. 5. FIG. 5 is a flowchart of the control method of the power supply system of the present invention. First, in step S1, an electrochemical three-electrode system 3 including a working electrode 32, a reference electrode 33, and an auxiliary electrode 31 is prepared. Next, in step S2, the two output terminals 23 and 22 of the power unit 2 are connected to the working electrode 32 and the auxiliary electrode 31, respectively, and the power unit 2 outputs an output current for polarizing the working electrode 32. Then, in step S3, the control unit 5 detects a signal reflecting the voltage between the working electrode 32 and the reference electrode 33, and adjusts the output current based on the signal.

[0019] Hereinafter, a method for maintaining a signal within a predetermined voltage range will be described in more detail. Refer to FIG. 6 in conjunction with FIGS. 1 and 4. FIG. 6 is a voltage signal-current waveform diagram showing the output current and voltage signal in the third stage of the power supply system shown in FIG. 1. The Y-axis of FIG. 6 is the output current supplied from the power unit 2, and the X-axis is a signal reflecting the voltage between the working electrode 32 and the reference electrode 33. Compared with FIG. 4, the static current in FIG. 6 is in a dynamically adjustable range, while the static current in FIG. 4 is basically a fixed value. In this embodiment, there are an upper limit value and a lower limit value in a predetermined current range within the control unit 5. The upper limit value of the current range is, and the lower limit value of the current range is, which may be equal to or different from, and im is the intermediate value. This current range corresponds to the stable passivation region in the polarization curve shown in FIG. 4. When the control unit 5 detects a signal reflecting the voltage between the working electrode 32 and the reference electrode 33, compares the signal with the voltage range, and confirms that the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 is below the lower limit value of the voltage range, the control unit 5 controls the output current supplied from the power unit 2 to decrease, and decreases the output current from a high current value back to im (as shown by "current decrease" in FIG. 6), thereby preventing the corrosion reaction that continues under overcurrent from being too fast. The lower limit value of the voltage range reflects the transpassivation potential of the polarization curve of the working electrode. When the control unit 5 detects a signal reflecting the voltage between the working electrode 32 and the reference electrode 33, compares the signal with the voltage range, and confirms that the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 is above the upper limit value of the voltage range, the control unit 5 controls the output current supplied from the power unit 2 to increase, and increases the output current from a low current value back to im (as shown by "current increase" in FIG. 6), so that the state of the working electrode 32 shifts toward the transition region between metal activation and passivation. That is, it is possible to prevent the working electrode 32 from being completely passivated at a low current and affecting the corrosion rate of the oxide film 32b. The upper limit value of the voltage range reflects the critical passivation potential of the polarization curve of the working electrode.As can be seen from the above, the output current supplied from the power unit 2 is within the current range and is dynamically adjusted according to the detection result of the signal reflecting the voltage between the working electrode 32 and the reference electrode 33. Thus, the corrosion state of the corrosion pit 32a of the working electrode 32 of the present invention is within the passive current action region of the polarization curve, and the effect of increasing the overall specific capacitance can be obtained. Of course, in one embodiment, the signal reflecting the voltage between the working electrode 32 and the reference electrode 33 may be the voltage value between the working electrode 32 and the reference electrode 33. At this time, the lower limit value of the voltage range is the value of the trans-passivation potential of the polarization curve of the working electrode, and the upper limit value of the voltage range is the value of the critical passivation potential of the polarization curve of the working electrode.

[0020] In some embodiments, the output current supplied from the power unit 2 has a hysteresis effect on the signal reflecting the voltage between the working electrode 32 and the reference electrode 33. As shown in FIG. 6, for example, when the control unit 5 controls the increase of the output current supplied from the power unit 2, the output current has a variable duty cycle and a variable current change rate, and the output current can be a continuous current waveform or a discrete current waveform. The corresponding voltage when the output current is in the rising state is different from the corresponding voltage when the output current is in the falling state, and a voltage difference value Vd can be obtained.

[0021] Refer to FIGS. 7A and 7B in conjunction with FIG. 1. FIGS. 7A and 7B are partial enlarged schematic views showing the structure of another embodiment in which corrosion holes are formed in the working electrode of the power supply system shown in FIG. 1. As shown in FIG. 7A, the working electrode 32 is further provided with a corrosion inhibitor 32c that blocks a part of the working electrode 32 and the corrosive liquid 4, thereby alleviating excessive corrosion on the surface of the working electrode 32, effectively controlling the pore coalescence phenomenon, being advantageous for the uniform distribution of the corrosion holes 32a on the surface of the working electrode 32, reducing the damage to the pore walls of the corrosion holes 32a, and deepening the corrosion tunnels. Also, a part of the current component (i2) in the output current supplied from the power unit 2 directly corrodes the working electrode 32 through the corrosion holes 32a, and the other current component (i1) in the output current needs to corrode the working electrode 32 through the corrosion inhibitor 32c. That is, the current component i2 in the output current supplied from the power unit 2 becomes larger than the current component i1, and the corrosive liquid 4 accurately corrodes the corrosion holes 32a, enhancing the corrosion efficiency, further increasing the volume of the corrosion holes 32a, that is, by changing the size of the corrosion holes 32a in FIG. 7A to the size of the corrosion holes 32a shown in FIG. 7B, the effect of improving the overall specific capacitance can be obtained. The shape of the corrosion holes 32a may be conical, cylindrical, pot-shaped, etc.

[0022] As described above, in the power supply system of the present invention, the control unit detects a signal reflecting the voltage between the working electrode and the reference electrode of the electrochemical three-electrode system, compares the signal with a predetermined voltage range, and according to the comparison result, maintains the signal within the voltage range (that is, between the critical passivation potential and the transpassivation potential), that is, adjusts the output current of the power unit within the current range so as to maintain the output current near the passivation current. Thereby, the corrosion holes generated at the initial stage of etching can continue to grow, improving the production efficiency of pore expansion, and promoting the formation and corrosion of the passivation film on the inner surface of the corrosion holes by adjusting the dynamic characteristics of the low passivation current in real time, effectively developing the corrosion holes in the depth direction, improving the production efficiency of the working electrode, improving the uniformity of the corrosion holes, and improving the overall specific capacitance. At the same time, the remaining thickness of the working electrode after corrosion is maintained uniformly, and the bending characteristics of the working electrode are improved.

Description of Reference Numerals

[0023] 1: Power supply system 2: Power unit 21: Control terminal 22, 23: Output terminals 3: Electrochemical three - electrode system 31: Auxiliary electrode 32: Working electrode 32a: Corrosion pit 32b: Oxide film 32c: Corrosion inhibitor 33: Reference electrode 4: Corrosive liquid 5: Control unit L: Depth r1: Radius ip: First current ib: Second current S1, S2, S3: Steps

Claims

1. A control method applied to a power supply device, comprising: (a) preparing an electrochemical three-electrode system including a working electrode, a reference electrode, and an auxiliary electrode; (b) connecting two output terminals of a power unit of the power supply device to the working electrode and the auxiliary electrode respectively, the power unit outputting an output current for polarizing the working electrode; (c) a control unit of the power supply device detecting a signal reflecting a voltage between the working electrode and the reference electrode, and adjusting the output current based on the signal, wherein the output current has a hysteresis effect on the signal. A control method.

2. The step (c) further includes comparing the signal with a predetermined voltage range, and adjusting the output current within a predetermined current range so as to maintain the signal within the predetermined voltage range according to a comparison result. The control method according to claim 1.

3. When the signal is less than or equal to a lower limit value of the voltage range, the control unit controls the output current to decrease; When the signal is greater than or equal to an upper limit value of the voltage range, the control unit controls the output current to increase. The control method according to claim 2.

4. The upper limit value of the voltage range reflects a transpassivation potential of a polarization curve of the working electrode, and the lower limit value of the voltage range reflects a critical passivation potential of the polarization curve. The control method according to claim 3.

5. The signal is a voltage between the working electrode and the reference electrode, the upper limit value of the voltage range is the transpassivation potential of the polarization curve of the working electrode, and the lower limit value of the voltage range is the critical passivation potential of the polarization curve. The control method according to claim 4.

6. The current range corresponds to a stable passivation region of a polarization curve of the working electrode. The control method according to claim 2.

7. Between the step (a) and the step (b), the method further includes providing a corrosion inhibitor on the working electrode to block a part of the working electrode and a corrosive liquid. The control method according to claim 1.

8. The working electrode is a metal foil, the auxiliary electrode is a titanium plate, and the reference electrode is a saturated calomel electrode. The control method according to claim 1.

9. A power supply device used in an electrochemical three-electrode system including a working electrode, a reference electrode, and an auxiliary electrode, A power unit including two output terminals respectively connected to the working electrode and the auxiliary electrode, and outputting an output current for polarizing the working electrode. A control unit that detects a signal reflecting the voltage between the working electrode and the reference electrode and adjusts the output current based on the signal. The output current has a hysteresis effect on the signal. A power supply device.

10. The power supply device according to claim 9, wherein the control unit compares the signal with a predetermined voltage range and adjusts the output current within a predetermined current range so as to maintain the signal within the predetermined voltage range according to the comparison result.

11. When the signal is equal to or lower than the lower limit value of the voltage range, the control unit controls the output current to decrease. The power supply device according to claim 10, wherein when the signal is equal to or higher than the upper limit value of the voltage range, the control unit controls the output current to increase.

12. The power supply device according to claim 11, wherein the upper limit value of the voltage range reflects the over-passivation potential of the polarization curve of the working electrode, and the lower limit value of the voltage range reflects the critical passivation potential of the polarization curve.

13. The power supply device according to claim 12, wherein the signal is the voltage value between the working electrode and the reference electrode, the upper limit value of the voltage range is the value of the over-passivation potential of the polarization curve of the working electrode, and the lower limit value of the voltage range is the value of the critical passivation potential of the polarization curve.

14. The power supply device according to claim 10, wherein the current range corresponds to the stable passivation region of the polarization curve of the working electrode.

15. The power supply device according to claim 9, wherein the output current has a hysteresis effect on the signal.

16. The power supply device according to claim 9, wherein a corrosion inhibitor is provided on the working electrode to block a part of the working electrode and the corrosive liquid.

17. The power supply device according to claim 9, wherein the working electrode is a metal foil, the auxiliary electrode is a titanium plate, and the reference electrode is a saturated calomel electrode.

18. A power supply system including the power supply device according to any one of claims 9 to 17 and an electrochemical three-electrode system.

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